JP2000091231A - Method for growing polycrystal and manufacturing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To crystallize an amorphous or polycrystalline material having a large area without causing any nonuniform polycrystallization due to overlapping by forming a dot-like, linear, or planar luminous flux by using the light emitted from a semiconductor light emitting element, and irradiating an object with the luminous flux. SOLUTION: A plurality of semiconductor lasers 11 is mounted on a laser generator 10 in a state where the lasers 11 are arranged in an array-like state. Since the lasers 11 are arranged in the array-like state, a desired laser beam, such as a dot-like, linear, or planar laser beam can be formed without any restriction on the beam size. Therefore, an object l5 can be polycrystallized by irradiating the whole surface of the object 15 by one time of scanning by forming, for example, a linear laser beam having the length corresponding to the width of the object 15. Alternatively, a plurality of areas scattered on a substrate can be irradiated separately by projecting a plurality of dot-like luminous fluxes upon the areas. When the object to be absorbed is amorphous silicon, it is preferable to adopt a semiconductor laser using a gallium nitride semiconductor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and a device for growing a polycrystal. More specifically, the present invention relates to a polycrystal growth method and a manufacturing apparatus for crystallizing an amorphous crystal or a polycrystal by heating.

[0002]

2. Description of the Related Art An electron beam or RTA (rapid thermal anneal) is used.
ing), a process of melting and solidifying an amorphous silicon (a-Si) thin film to form polycrystalline silicon (poly-Si) enables low-temperature crystal growth. For this reason, for example, a large TFT (th
In film transistor) Application to liquid crystal displays is expected. Among them, a-Si having a thickness of about several tens nm (nanometers) is formed on a glass substrate by a plasma CVD method.
Attention has been paid to a technique of forming a polycrystalline silicon film by depositing a film and irradiating the film with a pulse of XeCl laser light having a wavelength of 308 nm.

[0003] The reason for using the XeCl laser is that the optical absorption efficiency of amorphous Si is high near the wavelength of the laser, so that the desired amorphous S can be used without melting the underlying glass substrate.
that only the i-layer can be polycrystallized, or
High throughput can be expected by irradiating a large area by taking advantage of the characteristics of large output oscillation.

In such a technique, a laser beam taken out from a laser beam generator is generally expanded or condensed while irradiating the laser beam with uniformity of light intensity by an optical lens. The resulting irradiation size is about 0.6J
A current laser beam generator having a maximum irradiation energy of the class has a width of about 200 μm and a length of about 20 cm. The irradiation area is such that the laser beam irradiated on the amorphous or polycrystal is recrystallized after melting in some cases, and as a result, the amount of heat necessary to obtain the desired polycrystal grain size is applied to the irradiated body. Realistic value to give. That is,
With the laser beam size enlarged to about one digit larger than the size, energy per unit area sufficient to perform the crystallization is not supplied to the irradiation target,
It is impossible to obtain the desired polycrystal.

On the other hand, the size of a liquid crystal display mounted on, for example, a portable personal computer (PC) is increasing year by year, and the current mainstream is becoming a 12-inch type. It is no surprise that portable PCs with displays larger than 13 inches will become mainstream in the near future. In order to secure the 13-inch display, a rectangular display area having a size of about 27 cm and about 20 cm in the longitudinal direction and the transverse direction is required. Here, in an actual liquid crystal display device, around a display unit for displaying an image,
It is necessary to arrange a driver circuit for driving each pixel of the display unit. One of the advantages that polycrystalline silicon is applied to a display device is that semiconductor elements of both the display portion and the driver circuit for driving can be formed by polycrystal formed on one substrate. It is. On the contrary,
In the case of a display device using amorphous crystals, it is necessary to externally mount a semiconductor chip for driving pixels. In other words, when using polycrystalline silicon,
It is possible to reduce both the number of parts and the number of manufacturing steps.

On the other hand, as an area for incorporating the driver circuit, one more area is provided around a display section necessary for image display.
An area with a width of about cm is required. That is, in order to manufacture a large-sized liquid crystal display device exceeding 13 inches, it is necessary to polycrystallize a region where the short side of the longitudinal direction is about 29 cm and 22 cm respectively.

[0007]

However, when a conventional laser generator is used, one screen cannot be formed by one irradiation scan when manufacturing a large-area display exceeding 13 inches. Thus, it is necessary to perform irradiation scanning twice or more by overlapping the ends of the laser beam.
However, in the portion where the laser beams overlap, the irradiation amount of the laser light is larger than in other portions, and the variation in the grain size of the polycrystal may be larger than in other portions. As a result, in the semiconductor element manufactured using the polycrystalline silicon obtained in this way, non-uniformity of electrical characteristics due to non-uniformity of polycrystal occurs. This non-uniformity causes point defects, line defects, and non-uniform contrast of display surface elements on the display.

Hereinafter, this problem will be described in more detail with reference to the drawings.

FIG. 10 is a conceptual diagram showing a method of polycrystallizing amorphous silicon using a conventional XeCl laser. With a XeCl laser of about 0.6 J class, a laser beam having a size of several cm square can be extracted from the laser generator 111. This ray has a light intensity distribution approximated by a Gaussian distribution. Therefore, before introducing the amorphous silicon into the glass substrate, the homogenizer (homo-
A laser beam having a uniform intensity distribution is formed via a convergent lens system 114 and a convergent lens system 114, and finally is guided onto a substrate to be irradiated 115 via a mirror 18 which guides the laser beam to an irradiation position.

[0010] Here, the beam size is limited to a predetermined size because a light intensity density for melting and polycrystallizing the amorphous silicon is required. For example,
The upper limit is a beam size of about 200 μm in width and 20 cm in length as described above. The largest liquid crystal display that fits this size is about 12 inches. Therefore, in order to realize a liquid crystal display of a size larger than this, it is necessary to scan a part of the glass substrate for irradiation for polycrystallization, and then scan the part of the glass substrate with a laser so that the ends overlap. . That is,
Since the width of the laser beam is narrower than the desired irradiation area on the irradiation target substrate, two or more scans must be performed to polycrystallize the desired irradiation area.

Here, the grain size of the polycrystal in the portion where the laser beam is superimposed becomes non-uniform as compared with the other irradiated portions, and the non-uniformity is caused by the electric property of the semiconductor device directly formed on the other crystal. Resulting in non-uniformity of the mechanical properties. For example, the mobility of a TFT fabricated on a uniform polycrystal having a particle size of 0.2 μm is about 50 cm ² / V · s ±
It falls within the range of 10%. That is, the mobility is 45 to 55
cm ² / V · s. On the other hand, the particle size of the portion where the laser beams overlap is dispersed in the range of about 0.1 to 0.5 μm. When a TFT is manufactured on a particle size having such a distribution, the mobility varies in the range of ²⁰ to 80 cm ² / V · s.

As a result, when a liquid crystal pixel portion is formed in this portion, extremely linear or dot-like luminance unevenness occurs, or contrast becomes nonuniform. Therefore, in order to produce a uniform polycrystal, a polycrystallization method that does not cause superposition is required, and in the case of producing a large-area display, a linear beam having a length sufficient for its size is required. is necessary.

On the other hand, as a result of a study by the present inventors, it has been found that another cause of the variation in the crystal grain size is a variation in the output of the laser beam.
That is, this variation causes non-uniformity of the polycrystal, and also becomes a factor of narrowing the process margin. For example, in a polycrystallization process in which the allowable range of irradiation energy is 370 to 430 mJ / cm ² , if there is a 5% peak-to-peak beam intensity variation, the center energy is 400 m
Polycrystallization can be performed under the condition of J / cm ² ,
Central energy exceeds 410 mJ / cm ² or 3
When it is less than 90 mJ / cm ² , the above-mentioned allowable value is deviated due to a variation in strength, and a desired polycrystalline particle size cannot be obtained. That is, the apparent irradiation energy margin is (430-
370) = even 60 mJ / cm ^2, the actual process tolerance species circumference is 20 mJ / cm ² degree and narrow.

As described in detail above, in the conventional crystallization process using a XeCl laser, there are restrictions on the irradiation area and the narrow process margin.

In order to solve these problems, a method of performing scanning irradiation without forming an overlapping area has been studied, but no specific solution has been disclosed. On the other hand, in order to increase the beam size, it is necessary to improve the oscillation output of the laser device. However, in the current technology, laser oscillation at high output increases the fluctuation range of the laser light intensity, and as a result, the distribution of the crystal grain size of the obtained crystal also increases. Non-uniformity of the device characteristics of the semiconductor device cannot be avoided.

Under the circumstances described above, there is a long-felt need for a method of eliminating the non-uniformity of the particle size caused by the above-mentioned overlapping region.

The present invention has been made in view of such circumstances. That is, the present invention performs crystallization of a large-area amorphous or polycrystalline material exceeding the current laser beam size without causing non-uniformity of the polycrystal due to the overlap, and as a result, It is an object of the present invention to provide a method for producing a polycrystal capable of producing a low-cost and high-performance liquid crystal display and an apparatus for producing the same.

[0018]

In order to achieve the above object, the present inventor has proposed a gas laser generator having an output which is much closer to a point light source and whose output is unstable. Attention was paid to a semiconductor light emitting device capable of forming a uniform laser beam.

That is, the method for growing a polycrystal of the present invention comprises:
A polycrystal growth method in which an irradiation target in an amorphous or polycrystal state is polycrystallized by light irradiation, wherein a point-like, linear, or planar light beam is emitted using light emitted from a semiconductor light emitting device. And irradiating the light beam to the irradiation object to form the polycrystal.

The light beam has a length extending from one end to the other end of the irradiation object in any direction on the irradiation object, and the light beam and the irradiation object are arranged in one direction. The entire surface of the object to be irradiated is irradiated with light by relatively moving the object along.

[0021] Further, the present invention is characterized in that a temporal variation of the intensity of the light emitted from the semiconductor light emitting element or a distribution of a light irradiation amount on an irradiation surface of the irradiation object is suppressed to within 5%. .

Further, a plurality of the semiconductor light emitting elements are arranged at intervals, and a plurality of areas scattered on the irradiation object are irradiated.

Further, the temperature gradient in the in-plane direction of the irradiation surface to be irradiated with the light is set to 100 ° C./μm or more in the process of melting and solidifying the irradiated object by the light irradiation.

On the other hand, the apparatus for producing a polycrystal according to the present invention
It comprises each means configured to carry out the growth method described above.

[0025]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a conceptual diagram showing a polycrystal growth method according to the present invention. That is, in the method shown in the figure, a linear laser beam is emitted from the laser generator 10, and the irradiation target 15 is scanned and irradiated with the laser beam. In FIG. 1, a plurality of semiconductor lasers 11 arranged in an array are mounted on a laser generator 10. By arranging the semiconductor lasers 11 in an array, a desired point-like, linear or planar light source can be formed without limitation on the beam size. Therefore, for example, a linear laser beam having a length corresponding to the width of the irradiation target 15 can be formed, and the entire surface of the irradiation target 15 can be irradiated by one scan to perform polycrystallization. Further, as will be described later in detail, a plurality of dot-like light beams can be emitted to irradiate each of a plurality of regions scattered on the substrate. That is, according to the present invention, as in the case of the XeCl gas laser described above, the overlapping portion of the beam is not formed by dividing and scanning the irradiation object 15, and the crystal grain size caused by such overlapping portion is not formed. Can be eliminated.

The material and structure of the semiconductor laser 11 can be appropriately selected according to the light absorption characteristics of the object to be irradiated. For example, when the object to be absorbed is amorphous silicon, it is desirable to employ a semiconductor laser using a gallium nitride-based semiconductor, as described later in detail. In addition,
In the present specification, “gallium nitride based semiconductor” refers to B
_{x In y Al z Ga (1} -xyz) N ( where, O ≦ x ≦ 1, O
≦ y ≦ 1, and O ≦ z ≦ 1. )) And a mixed crystal containing phosphorus (P), arsenic (As), etc. in addition to N as the group V element.

In addition to gallium nitride based semiconductors, for example, ZnS based, ZnSe based, ZnSSe based or S
Even if an iC-based material is used, laser light in a short wavelength band can be obtained. Further, as a material of the semiconductor laser 11, other than these materials, for example, an AlGaAs-based material,
Materials such as P-based and InGaAlP-based materials may be used. When these materials are used, the wavelength of the laser beam is long, so if necessary, SHG (second harmonic genaratio) may be used.
(n: second harmonic generation) It is more desirable to convert the wavelength to the vicinity of the absorption peak wavelength of amorphous silicon using an element or the like.

Further, instead of the semiconductor laser 11, a light emitting diode (LED: light emitting device) may be used.

The output fluctuation of a semiconductor laser or LED is 1% or less, which is much smaller than that of a XeCl laser. For this reason, the grain size of the polycrystal produced by this process is more uniform than before, and it is possible to realize a high-performance liquid crystal display.

Further, according to the present invention, a laser beam can be formed in accordance with the size of the irradiation object, so that the optical system can be simplified as compared with the related art. As a result, the laser light system including the optical system is simplified,
The size can be reduced to about 1/10. As a result, the controllability and reliability of the laser beam are dramatically improved,
Maintenance and handling are also easy.

As described above, according to the present invention, by using the laser light generator 10 using a point-like, linear, or near-surface light source using a semiconductor laser element, in principle, any size of the irradiation target can be obtained. The whole body can be polycrystallized by one scan irradiation even for the body. As a result, it is possible to provide a process applicable to a large-sized liquid crystal display device expected in the market. In addition, the optical system that introduces the laser beam into the substrate is simplified compared to the conventional example, and by using a stable light source with less fluctuation in light intensity, space saving, high reliability, expansion of the process margin, etc. are achieved. Various effects can be obtained.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below by taking as an example a case where amorphous silicon deposited on a glass substrate is polycrystallized.

FIG. 2 is a conceptual diagram illustrating an embodiment of the present invention. In the figure, semiconductor lasers 1 arranged in an array
As 1, a semiconductor laser made of a gallium nitride based semiconductor is used. By arranging the semiconductor lasers 11 in an array, a desired point-like, linear or planar laser light can be formed without limitation on the beam size.

In the present embodiment, 0.5 m
A linear laser beam is formed by arranging 600 gallium nitride based semiconductor lasers 11 in an array at m intervals. When operating the laser elements 11 arranged in an array at a high output, it is desirable to provide a cooling mechanism for maintaining stable operation for a long time.

The oscillation wavelength of the semiconductor laser 11 is preferably in the vicinity of 300 nm where the absorption efficiency of amorphous silicon or polycrystalline silicon is high. When gallium nitride (gallium nitride) is used as the active layer of the semiconductor laser 11, the oscillation wavelength is about 420 nm.
By increasing the band gap by adding boron (B) or aluminum (Al) to aN, the oscillation wavelength becomes 3
00 nm.

On the other hand, as a result of the study by the present inventors, the irradiation target 1
When polycrystallizing 5 by irradiating a laser beam to 5,
In the process of solidifying the amorphous silicon layer deposited on the substrate after melting, the horizontal temperature gradient is 100 ° C./μm.
As described above, it has been found that it is desirable to adjust the intensity distribution at the beam end of the laser beam and the scan speed. In the case of a conventional polycrystallization process using a XeCl gas laser, it was required that the laser pulse irradiation time be about 20 nanoseconds and the horizontal temperature gradient be about 500 ° C./μm or more. However, it is not easy to form such a steep temperature gradient, and there has been a problem that the apparatus becomes complicated and the throughput decreases. On the other hand, according to the present invention, since the semiconductor laser is used, the irradiation time of the laser can be made longer than that of the conventional gas laser. When the laser irradiation time was set to about 100 to 200 nanoseconds and the horizontal temperature gradient was set to 100 ° C./μm or more, it was found that polycrystallization at the same level or more as that of the related art was possible.

According to the present invention, the temperature gradient in the horizontal direction can be made gentler than in the prior art, so that the configuration of the apparatus is simplified, and the advantage that a temperature heating mechanism and the like are not required is obtained.

In the present embodiment, each semiconductor laser 11 is driven at a voltage of 3 volts, a current of 100 milliamps, a pulse width of 100 nanoseconds, and a frequency of 0.5 kilohertz. The size of the laser beam extracted under these driving conditions is adjusted by an optical system installed between the light source and the irradiation target 15. As the optical system, basically, a combination of a homogenizer 13 for making the laser beam intensity uniform and a lens system 14 for focusing and parallelizing the laser beam to a desired size is used.

These optical systems are adjusted according to the light output characteristics and the irradiation size of the semiconductor laser 11, and include a magnifying lens,
In some cases, a combination of optical elements such as a rod (lod) lens, a semi-cylindrical lens, a concave mirror, a convex mirror, or a hologram is required. It is desirable that the spatial intensity fluctuation of the irradiation light in the irradiation area be suppressed to within 10%, and preferably within 5%. For this purpose, it is necessary to design an optical system that homogenizes the spatial distribution of the beam intensity using the homogenizer 13. In order to scan the laser beam uniformized in this manner on the irradiation object 15, a mirror scan method is effective.

By scanning the linear laser beam having the desired length formed as described above with the scanning mirror 18, the entire surface of the irradiation target 15 having the desired size can be polycrystallized by one scan. Can be processed. Further, instead of scanning the laser beam, the irradiation target 15 may be moved. The laser beam formed using the above optical system has a width of about 100 μm on the irradiation object, and the intensity unevenness in the beam is within 1%. By expanding or reducing this laser beam using an optical system as appropriate, or by arranging a plurality of laser arrays themselves, a laser beam of a desired size corresponding to a display of 13 inches or more can be freely obtained. .

The irradiation object 15 of this embodiment is an object in which an amorphous silicon layer of about 50 nm is deposited on a normal glass substrate by PECVD (plasma CVD). The object to be irradiated was irradiated with the above laser beam only to a desired region. Here, in order to realize a laser beam in which fluctuations in light intensity are suppressed, it is essential to increase the stability of the laser light emitting device itself. In this point, unlike a gas laser such as XeCl, in which adjustment of the laser resonator main body is difficult, in the case of the semiconductor light emitting devices arranged in an array according to the present invention, the intensity difference between the devices, that is, the variation is individually adjusted. Can be done. The light intensity fluctuation of each light emitting element can be achieved by measuring the intensity of each light emitting element and controlling the supplied power, and the light output control can be performed manually as well as automatically.
Therefore, there is an advantage that a stable operation in which spatial and temporal light intensity fluctuations are suppressed can be performed. As a result, it is possible to suppress the light intensity fluctuation in the irradiation area to 5% or less.

FIG. 3 is a schematic diagram showing the grain size of the polycrystal formed according to this embodiment. That is, FIG.
SEM (field emission-scanning electron microsco
pe). As described above, the irradiation object is obtained by depositing an amorphous silicon layer having a thickness of 50 nm on a normal glass substrate by a plasma CVD method.

FIG. 4 is a schematic diagram showing, as a comparative example, the grain size of a polycrystal produced by a conventional method. This figure also shows FE
−SEM (field emission-scanning electron micros
cope). This polycrystal uses a XeCl laser having a maximum irradiation energy of 0.6 J class,
The optical system is polycrystallized with a beam size of about 200 μm in width and 10 cm in length. The irradiated object is
Cut from the same substrate as used in FIG.

At the time of polycrystallization, the laser beam having a width of 200 μm is irradiated for one time with an irradiation time of 20 nanoseconds.
Irradiated 0 times. In FIG. 4, the average grain size of the polycrystal is about 0.2 μm, but its variation is 0.05 to 0.5 μm.
It extends over a range of 3 μm, with a variation of about 25-150%. This variation causes non-uniformity of TFT elements formed thereon, resulting in defective lighting of pixels and non-uniformity of contrast. Such variation in the particle size strongly depends on the light intensity fluctuation of the irradiation laser light. The gas laser used in this comparative example had a 15% intensity variation.
As described above, it is difficult to control the crystal grain size as described above, resulting in a variation in the grain size as shown in FIG.

On the other hand, as shown in FIG. 3, according to the present embodiment, the average grain size of the polycrystal is also about 0.2 μm, but the variation is 0.1 to 0.3 μm. Within the range, the variation is reduced to about 50 to 150%. In particular, according to the present embodiment, the crystal grains having a small particle size are reduced,
It can be clearly seen from FIG. 6 that the particles have a uniform size. That is, by the effect of the present invention, the particle size distribution of the polycrystal obtained after the polycrystallization process was reduced by half. This effect is attributable to the fact that the variation in irradiation energy was suppressed as compared with the conventional example. In the present embodiment, the fluctuation of the irradiation energy is suppressed to about 5%, but when the irradiation energy is further reduced to about 2% or less, a more uniform crystal grain distribution can be obtained.

As described above, according to the present invention, it is possible to produce a much more uniform polycrystal than the conventional one by eliminating the overlapping portion of the laser beams and suppressing the output fluctuation of the beam intensity at the same time. Become. The present invention is an essential element for realizing high performance and high definition of a large liquid crystal display, and cannot be realized by the conventional method.

In the above-described embodiment, the case where the pulse laser beam is irradiated is described. However, the same effect can be obtained even when the laser beam is continuously irradiated. That is, by irradiating the object to be irradiated with a pulse or continuously according to the situation, fine adjustment according to the characteristics of the thin film to be crystallized is possible.

Further, if the wavelength of the semiconductor laser is selected, the method of the present invention is effective not only for the silicon of the present embodiment but also for the polycrystallization of various superconducting materials, compound materials, organic materials, insulating materials and the like. It is.

On the other hand, in the case of the conventional example using the above-described gas laser, the laser oscillation time per pulse is 20 nanoseconds. Irradiation time can also be selected. Specifically, the irradiation time can be extended up to about 200 nanoseconds, and the polycrystallizable time of the polycrystal can be controlled in this manner. We can expect condition.

In FIG. 2, a light splitter (not shown) may be provided between the homogenizer 13 and the irradiation object 15 to irradiate a plurality of areas scattered on the substrate. That is, according to the present invention, the laser light emitted from each of the semiconductor lasers 11 is once collected by the homogenizer 13 so that the intensity variation of the beam is averaged, and then, if necessary, the laser light is divided as necessary. In addition, the intensity of any of the beams can be made uniform in principle.

In the above-described embodiment, the case where the light emission from the laser element is used as it is is exemplified. However, other than this, for example, a wavelength conversion element may be used. FIG. 5 is a conceptual diagram illustrating a case where a harmonic generation element is used. That is,
In the example shown in the figure, a laser beam having a predetermined wavelength can be obtained by using the harmonic generator 21 using the red laser 11 as an excitation light source. As the harmonic generation device 21, for example, a second harmonic generation element (SHG) using a KTB crystal or a BBO crystal can be used. Further, it may be converted to a third harmonic or higher harmonic. The harmonics obtained in this manner are irradiated on the irradiation target 15 via the lenses 14 and 19 and the mirror 18.

Further, the laser element 11 is not limited to a point emission type element, and the same effect can be obtained by using a surface emission type laser element.

FIG. 6 is a perspective view showing an example of a laser beam generator. That is, as shown in the figure, by stacking the element arrays 11 in a stack and providing the cooling mechanism 57 therebetween, high-output and more stable operation can be performed. As the cooling mechanism 57, for example, a water cooling mechanism or an electronic cooling mechanism using a Peltier element or the like can be used. By using such a cooling mechanism, it is possible to increase the oscillation output during continuous oscillation, which often cannot be increased as compared with pulse oscillation.

FIG. 7 is a conceptual diagram exemplifying a case where light-emitting elements as light sources are arranged in a curved line. When a curved laser beam is irradiated compared to a laser beam having a linear beam shape, the crystal grains on both sides of the crystal grains crystallized at the head of the laser beam are crystallized later than the head crystal grains. Crystal growth can be controlled as is done. As a result, it is possible to realize polycrystal grains larger than before.

When scanning without fixing the irradiation position, crystal growth in the direction perpendicular to the scanning direction of the laser beam also proceeds. In this case, a longer crystallization time can be ensured, so that by appropriately adjusting the beam shape, crystal grains having a larger size can be obtained as compared with the case of simply irradiating a linear laser beam. In addition, it is particularly effective when a pulse oscillation light emitting element is used, and the oscillation output can be expected to be improved as compared with the case where a continuous oscillation light emitting element is used. There are many benefits, such as: In the case of continuous oscillation, the effect can be obtained by scanning the substrate at a crystallization speed of, for example, 1 millimeter / second or more. If crystallization is possible, scanning at a speed of 1 cm / sec or more is desirable.

FIG. 8 shows an embodiment in which laser light is applied only to the TFT portion of the liquid crystal display device. That is, the laser elements 11 are arranged so that the laser light is irradiated only to the portion 15a where the TFT is formed in the irradiation target, or only the elements at predetermined positions of the laser elements 11 arranged in an array are arranged. To work. At this time, the substrate and the array are relatively positioned, that is, in this embodiment, the irradiation target 1 is
5 is moved in the direction of the arrow in the figure, and is appropriately irradiated with laser light.

In the case of this embodiment, since it is not necessary to irradiate the entire surface of the substrate, it is possible to reduce the number of light-emitting elements to be driven, and to simplify and reduce the size and weight of the device.
It is possible to realize a low power consumption type polycrystallization apparatus. Also, unlike polycrystallization of the entire surface of the substrate, cost reduction can be expected by improving the throughput.

Further, according to this embodiment, it is possible to manufacture a liquid crystal display device having higher performance and higher reliability than the conventional one at a high yield. That is, it is generally recognized that when amorphous silicon or fine polycrystalline silicon is polycrystallized by laser annealing, its surface becomes uneven, and "projections" are generated at crystal grain boundaries, particularly at the triple point of the grain boundaries. The so-called “array substrate” that constitutes the liquid crystal display device has an “auxiliary capacitance section” using an insulating film as a capacitor together with a TFT. Decrease. As a result, there have been problems such as display unevenness due to a change in storage capacity, reduction in reliability, and reduction in manufacturing yield.

On the other hand, according to the present embodiment, it is possible to efficiently polycrystallize only the TFT portion 15a in the irradiation target, that is, the array substrate. That is, if the auxiliary capacitance portion is not irradiated with the laser beam, the occurrence of “projections” can be suppressed, and the above-described problems of short-circuiting of the insulating film and reduction in withstand voltage can be solved. As described above, according to the present embodiment, the “projection” of the polycrystalline silicon in the auxiliary capacitance portion
, A large-sized liquid crystal display device having high quality and high reliability can be stably manufactured.

FIG. 9 is a conceptual diagram showing an example in which laser light is emitted from a plurality of laser elements arranged two-dimensionally.
That is, an embodiment in which a plurality of light emitting devices 10 in an array are provided in parallel so as to irradiate only the TFT portion 15a of the liquid crystal display device 15 which is an object to be irradiated. In this case, it is not necessary to irradiate the entire surface of the irradiation object 15, and all the TFT portions 15a on the substrate can be polycrystallized at one time. Therefore, it is not necessary to move the irradiation object or the laser device, and it is possible to realize a low power consumption type polycrystallizing apparatus as well as simplification, miniaturization, and weight reduction of the apparatus. Also, unlike polycrystallization of the entire surface of the substrate, cost reduction can be expected by improving the throughput. Further, similarly to the above-described embodiment, the "protrusion" of the auxiliary capacitance portion is eliminated, and a liquid crystal display device having high quality and high reliability can be manufactured at low cost and high yield.

[0062]

As described in detail above, according to the present invention,
Since a laser beam adjusted to a desired linear or planar size, which has been difficult in the past, can be easily formed, when polycrystallizing a large area region, the beam ends are overlapped to form a multi-region. It is not necessary to perform crystallization, and polycrystallization of a desired area can be performed by one scan.

Accordingly, it is possible to more uniformly polycrystallize a desired area without causing nonuniform portions of polycrystal due to overlapping beam ends.

Further, according to the present invention, the fluctuation of the light output of a semiconductor laser used as a light source can be suppressed much smaller than that of a gas laser such as XeCl.
As a result, the grain size of the polycrystal produced by using the present invention becomes more uniform, so that the performance of various devices such as a liquid crystal display can be improved.

Further, according to the present invention, the optical system can be simplified as compared with the related art. Furthermore, the size of the laser device main body can be reduced to 1/10 or less, and at the same time, the weight can be reduced.

As described above, according to the present invention, it is possible to achieve a more uniform polycrystallization than before, and to provide various devices such as a liquid crystal display device having high performance and high reliability at low cost and high yield. Can be manufactured,
The industrial benefits are enormous.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram illustrating a polycrystal growth method according to the present invention.

FIG. 2 is a conceptual diagram illustrating an embodiment of the present invention.

FIG. 3 is a schematic diagram showing a grain size of a polycrystal formed according to the present embodiment.

FIG. 4 is a schematic diagram of a comparative example showing the grain size of a polycrystal produced by a conventional method.

FIG. 5 is a conceptual diagram illustrating a case where a harmonic generation element is used.

FIG. 6 is a perspective view illustrating an example of a laser light generator.

FIG. 7 is a conceptual diagram illustrating a case where light-emitting elements serving as light sources are arranged in a curved line.

FIG. 8 illustrates an embodiment in which laser light is irradiated only to a TFT portion of a liquid crystal display device.

FIG. 9 is a conceptual diagram illustrating an example in which laser light is emitted from a plurality of laser elements arranged two-dimensionally.

FIG. 10 is a conceptual diagram showing a method of polycrystallizing amorphous silicon using a conventional XeCl laser.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Laser light generator 11 Semiconductor laser 13 Homogenizer 14, 19 Lens 15 Irradiation object 18 Mirror 21 Harmonic generator 57 Cooling means 111 Gas laser 113 Homogenizer 114 Optical system 115 Irradiation object

Claims (7)

[Claims] 1. A method for growing a polycrystal in which an irradiation target in an amorphous or polycrystalline state is polycrystallized by light irradiation, wherein a point, a line, or a line is formed using light emitted from a semiconductor light emitting element. Alternatively, a polycrystalline growth method is characterized in that a planar light beam is formed, and the light beam is irradiated on the object to be polycrystallized. 2. The light beam has a length extending from one end to the other end of the irradiation object in any direction on the irradiation object, and the light beam and the irradiation object are arranged in one direction. 2. The method of growing a polycrystal according to claim 1, wherein the entire surface of the irradiation object is irradiated with light by relatively moving the irradiation object along the surface. 3. The method according to claim 1, wherein a temporal variation of the intensity of the light emitted from the semiconductor light emitting element or a distribution of a light irradiation amount on an irradiation surface of the irradiation object is suppressed to within 5%. The method for growing a polycrystal according to claim 1. 4. A method for growing a polycrystal according to claim 1, wherein a plurality of said semiconductor light emitting devices are arranged at intervals and a plurality of regions scattered on said irradiation object are irradiated. 5. A temperature gradient in an in-plane direction of an irradiated surface to be irradiated with light during the process of melting and solidifying the irradiated object by the light irradiation is set to 100 ° C./μm or more. Item 5. The method for growing a polycrystal according to any one of Items 1 to 4. 6. A polycrystal manufacturing apparatus for polycrystallizing an object to be irradiated in an amorphous or polycrystalline state by light irradiation, comprising: a semiconductor light emitting element; A light beam forming means for forming a linear or planar light beam; and an irradiating means for irradiating the object with the light beam, wherein the polycrystallization is performed by irradiating the object with the light beam. An apparatus for producing a polycrystal, comprising: 7. The light beam forming means forms the light beam having a length extending from one end to the other end of the irradiation object in any direction on the irradiation object, and the light beam and the irradiation object are formed. 7. The apparatus for producing a polycrystal according to claim 6, wherein the apparatus is configured to irradiate the entire surface of the irradiation target with light by relatively moving the irradiation target in one direction.